This article is about the single most important piece of equipment you're going to buy: the lens. There are myriads of different lenses out there, and it's easy to get lost. But do not despair - this guide will help you make the right choice. First I'm going to talk about the different characteristics of a lens - among other things we'll learn about zoom vs. prime lenses, and why the f-number is so important. Then I'll move on to recommend a few lenses for each different budget!

Characteristics

Each lens is different. At first it can be a little bit intimating to navigate your way through the maze of choices, but once you learn the basics you can easily decide what you need and which lens satisfies your requirements.

Zoom vs. Prime

The biggest difference between lenses is their ability or inability to zoom. With a zoom lens you can - what a surprise - zoom. But it comes at a price: the image quality suffers and usually (and this is the crucial one) they have a lager f-number. I'll talk about f-numbers in a second. You can easily spot a zoom-lens as it has a range of focal-lengths. Just take a look at the label:

The first number is always the focal-length. In this case it's 18-270mm. So the range for this lens is 18mm to 270mm. A prime lens would only have one number, like 50mm. While the majority of photographers usually opt for a zoom lens, prime-lenses have their advantages: they are excellent for portraits, and are fantastic in low-light situations.

F-Number

Don't underestimate the f-number, like I did at first. It has an influence on lots of things. But what does the number mean? Well, to put it simply, it tells you how much light makes it through the lens and hits the sensor. The smaller the number the wider your camera's aperture is able to open. Usually it ranges between f/0.9 and f/6.3.

It's worth noting that zoom lenses don't always have a fixed f-number. As you can see in the image above, my 18-270mm lens ranges between f/3.5 and f/6.3 - which can be a pain. You can only set your aperture as wide as the f-number, and - in most cases - the lower this number, the better. The are a whole range of benefits that are too extensive to go into in this post alone!

Image Stabilization (IS/VR/DI)

Modern lenses often have some kind of image-stabilization on board. Canon calls it "Image Stabilization", Nikon "Vibration Reduction" and Tamron "Digitally Integrated". This is great! They basically let you use a longer shutter speed while maintaining a steady image - to a degree! Usually it's built into the lens, but a few manufacturers are starting to integrate it into the camera body itself. If you are looking for a new lens, look out for one with this handy feature.

Different Lens Choices

Now that you know what to look out for when buying a lens, I can give you an overview over the market and recommend a lens or two.

Wide-Angle Lenses

These are mostly used for stunning landscape images. As it isn't hard to get a sharp shot with a low focal-length and the landscape doesn't move, a larger F-Number will suffice. If you're not on a budget, grab yourself a Nikkor AF-S 14-24mm f/2.8. To date it is the sharpest lens, but with a price tag: the street price is about $2,000. Although it's quite expensive, with such unbelievable sharpness it's still a bargain - a brilliant piece of engineering.

If you're looking for something cheaper, I can recommend the Tokina AF 12-24mm f/4. For around $500 you'll get a solid lens with the only downsides being the strong vignetting and the barrel distortions at 12mm.

If you're looking for a fisheye, the Tokina AF 10-17mm f/3.5-4.5 could be a good choice. You don't get the best optics, but since a fisheye is an effect-lens this isn't necessarily all that important. It's still sharp enough for any purpose and you get good value for your around $600.

Medium-Range Lenses

This is your standard lens, which will work fine most of the time. To some people, a mid-ranged lens seems boring, because it doesn't deliver an extreme point-of-view. But think again - this can be an advantage if you need to take a picture "as the eye sees it". Think about shooting a portrait. This can't be done with a wide-angle lens.

If you have some money to spend, grab yourself either the Nikkor AF-S 24-70mm f/2.8G ED ($1,700) or the Canon EF 24-70 mm f/2.8 L USM ($1,400) depending on your system. Looking for a bargain? Then take a look at the Tamron AF 28-75mm f/2.8. It may not be perfect, but can be picked up for a bargain second hand so you don't have to dig deep in your wallet to afford it. And it delivers a lot for the money you spent: image quality, sharpness, build quality, compact size etc.

A real classic, and favourite of portrait photographers, is a fixed focal length 50mm lens. They are extremely fast, the images are crisp, they work well in low-light situations and best of all, they train your body, as you have to use your legs to "zoom". A whole range of different lenses are available depending on your camera type, and budget.

Telephoto Lenses

Fancy yourself as a wildlife or sport photographer? Then you are in need of a telephoto lens. It brings far away objects nearer, and flattens the distances between objects: just look at the sports page in any newspaper. These images are likely shot with a telephoto lens. Notice how the spectators appears to be the same size as the players, despite being 100 yards further away?

These are the most expensive lenses, due to the fact that it is difficult to build a high quality one. The light has to travel a long way before it reaches the sensor, so it's hard to conserve it. If you are an enthusiastic amateur, consider grabbing the Nikkor AF-S 70-200mm f/2.8 G IF-ED VR or the Canon EF 70-200mm f/2.8 USM L. The Nikkor has the better image quality and an image stabilization system (VR), which is quite important to have on a telephoto.

Both have a fast autofocus which is another important thing to look for on a telephoto - just think about trying to shoot fast moving animals. A good third-party alternative is the Sigma AF 70-200mm f/2.8 ($800). It's almost comparable in terms of quality, but doesn't come with image stabilisation. You decide!

Super-Zoom Lenses

If you're on holiday, wandering around a town, you don't necessarily want to carry all your lenses around all day. This is where super-zoom lenses come in. They provide a vast focal-length range. The best deal around is the Tamron AF 18-270mm f/3.5-6.3 DI II ($625). Since it the newest of all super-zoom lenses, it dominates the market fairly comprehensively.

The only downside is a slow auto-focus, which makes it a pain to shoot wildlife, insects or any fast moving subject. And the autofocus won't work properly on 270mm, as it needs at an aperture of least f/5.6. On the other hand, it has a superior image quality (compared to other super-zooms of course) and image stabilization. So grab it if you're looking to shoot landscapes, architecture, portraits and close-ups with only one lens.

Macro Lenses

Finally, we come to macro lenses. If you have a Nikon body, there is only one choice you really have: the famous Nikkor AF-S 105mm f/2.8G IF-ED VR. It's one of the sharpest, fastest lenses ever built, along with packing image stabilization. You can get it for around $800, but it's worth every penny. It's just pure fun to work with.

Canon offers the Canon EF 100mm f/2.8 USM macro ($600) which is still a great lens. One big downside though is the lack of a image stabilization system, which is very important when shooting macros. For half the price of Nikons lens, you'll get a Sigma AF 105mm f/2.8 EX macro DG (around $400). It's inferior in almost every aspect to the competition, but the low price is great if you're not sure whether macro photography is something you want to pursue.

Experiment, and Have Fun!

Choosing a lens doesn't need to be a difficult task. It's an exciting process, that always gives you the chance to learn more about photography and improve your skill set. Remember that the second hand market for lenses is always worth considering, and it gives you a fairly inexpensive way to experiment with different lenses and settle upon a kit that's right for you.

Have fun, and let us know in the comments which lenses we would find in your photography bag!